Field of the Invention
The present invention relates to a projection lens and a projector with a magnifying function. For example, the present invention relates to a wide-viewing-angle projection zoom lens suited to enlarge and project an image displayed on an image display element such as a digital micromirror device or an LCD (liquid crystal display) onto a screen, and a projector including the same.
Description of the Related Art
JP 2004-117519 A and JP 2005-106948 A propose zoom lenses suitable as projection lenses for projector. The zoom lenses described in JP 2004-117519 A and JP 2005-106948 A have four groups with negative, positive, negative, and positive lenses, five groups with negative, positive, negative, positive, and positive lenses, and six groups with negative, positive, negative, positive, positive, and positive lenses, or negative, positive, negative, negative, positive, and positive lenses. Therefore, the zoom lenses have a negative group-leading configuration in which the first lens group exerts negative refractive power, and they can be said to be useful as wider-angle projection lenses.
However, the zoom lenses described in JP 2004-117519 A and JP 2005-106948 A each have an about 1.2 magnification ratio that cannot be said to be a high value. In addition, many of the zoom lenses described in JP 2005-106948 A have a magnification chromatic aberration of about 10 to 15 μm. In the case of enlarging and projecting an image, the magnification chromatic aberration becomes significantly prominent, and the lenses cannot be said to be suited for projectors. When an attempt is made to achieve a high magnification ratio while correcting favorably the magnification chromatic difference, the amounts of movement of the respective lens groups become large to result in size increase of the projection lenses.